(19)

(11)

EP 0 505 382 A1

(12)

(43) Date of publication: 30.09.1992 Bulletin 1992/40 (21) Application number: 90917231.0 (22) Date of filing: 26.11.1990

(51) International Patent Classification (IPC):  H01F 5/ 00( . ) H01F 27/ 02( . ) H01F 27/ 29( . ) H01F 41/ 06( . ) H04R 1/ 06( . ) H04R 25/ 00( . ) H01F 5/ 04( . ) H01F 27/ 06( . ) H01F 41/ 00( . ) H01F 41/ 10( . ) H04R 9/ 04( . ) H04R 11/ 02( . ) (86) International application number: PCT/GB1990/001828 (87) International publication number: WO 1991/010243 (11.07.1991 Gazette 1991/15)

(84) Designated Contracting States: AT BE CH DE DK ES FR GB GR IT LI LU NL SE (30) Priority: 21.12.1989 GB 19890028899 (60) Divisional application: 95110964.4 / 0686985 (71) Applicant: Knowles Electronics Company Burgess Hill Sussex RH15 9LP (GB)	(72) Inventors: SALVAGE, Richard, James Burgess Hill West Sussex RH15 0NL (GB) HARRINGTON, Steven, John Steyning West Sussex BN44 3NE (GB) POWELL, Derek, William Burgess Hill West Sussex RH15 9HP (GB) (74) Representative: Dunlop, Brian Kenneth Charles, et al  c/o Wynne-Jones, Lainé & James 22 Rodney Road Cheltenham Gloucestershire GL50 1JJ Cheltenham Gloucestershire GL50 1JJ (GB)